001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.betwixt.io.read;
018
019 import java.util.ArrayList;
020 import java.util.Iterator;
021
022 /**
023 * <p>Chain implementation that's backed by a list.
024 * This is the default implementation used by Betwixt.
025 * </p><p>
026 * <strong>Note</strong> this implementation is <em>not</em>
027 * intended to allow multiple threads of execution to perform
028 * modification operations concurrently with traversal of the chain.
029 * Users who require this behaviour are advised to create their own implementation.
030 * </p>
031 *
032 * @author Robert Burrell Donkin
033 * @since 0.5
034 */
035 public class BeanCreationList extends BeanCreationChain {
036
037 //-------------------------------------------------------- Class Methods
038
039 /**
040 * Creates the default <code>BeanCreationChain</code> used when reading beans.
041 * @return a <code>BeanCreationList</code> with the default creators loader in order, not null
042 */
043 public static final BeanCreationList createStandardChain() {
044 BeanCreationList chain = new BeanCreationList();
045 chain.addBeanCreator( ChainedBeanCreatorFactory.createIDREFBeanCreator() );
046 chain.addBeanCreator( ChainedBeanCreatorFactory.createDerivedBeanCreator() );
047 chain.addBeanCreator( ChainedBeanCreatorFactory.createElementTypeBeanCreator() );
048 return chain;
049 }
050
051
052
053 //-------------------------------------------------------- Attributes
054 /** The list backing this chain */
055 private ArrayList beanCreators = new ArrayList();
056
057 //-------------------------------------------------------- Methods
058
059 /**
060 * Creates an Object based on the given element mapping and read context.
061 * Delegates to chain.
062 *
063 * @param elementMapping the element mapping details
064 * @param readContext create against this context
065 * @return the created bean, possibly null
066 */
067 public Object create( ElementMapping elementMapping, ReadContext readContext ) {
068 ChainWorker worker = new ChainWorker();
069 return worker.create( elementMapping, readContext );
070 }
071
072 //-------------------------------------------------------- Properties
073
074 /**
075 * Gets the number of BeanCreators in the wrapped chain.
076 * @return the number of <code>ChainedBeanCreator</code>'s in the current chain
077 */
078 public int getSize() {
079 return beanCreators.size();
080 }
081
082 /**
083 * Inserts a <code>BeanCreator</code> at the given position in the chain.
084 * Shifts the object currently in that position - and any subsequent elements -
085 * to the right.
086 *
087 * @param index index at which the creator should be inserted
088 * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
089 * @throws IndexOutOfBoundsException if the index is out of the range
090 * <code>(index < 0 || index > getSize())
091 */
092 public void insertBeanCreator(
093 int index,
094 ChainedBeanCreator beanCreator )
095 throws IndexOutOfBoundsException {
096 beanCreators.add( index, beanCreator );
097 }
098
099 /**
100 * Adds a <code>BeanCreator</code> to the end of the chain.
101 * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
102 */
103 public void addBeanCreator( ChainedBeanCreator beanCreator ) {
104 beanCreators.add( beanCreator );
105 }
106
107 /**
108 * Clears the creator chain.
109 */
110 public void clearBeanCreators() {
111 beanCreators.clear();
112 }
113
114 /** Worker class walks a chain */
115 private class ChainWorker extends BeanCreationChain {
116 /** Iterator for the creator list */
117 private Iterator iterator;
118 /** Creates the iterator */
119 ChainWorker() {
120 iterator = beanCreators.iterator();
121 }
122
123 /**
124 * @see BeanCreationChain#create
125 */
126 public Object create( ElementMapping elementMapping, ReadContext readContext ) {
127 if ( iterator.hasNext() ) {
128 ChainedBeanCreator beanCreator = (ChainedBeanCreator) iterator.next();
129 return beanCreator.create( elementMapping, readContext, this );
130 }
131
132 return null;
133 }
134 }
135 }